[. . . ] When choosing a power amplifier to use with your speakers, make sure that its power output matches the speakers' power capacity (refer to the Specifications). [. . . ] If it is not strong enough, reinforce the strength of the ceiling board with appropriate hardware. â· Yamaha will not be responsible for any accidents caused by a speaker that falls due to weak ceilings or inappropriate installation methods. Pay attention to the polarity, especially when installing multiple speakers. Note: Before connecting or disconnecting the speaker system from the amplifier, turn the amplifier off. [. . . ] Aligning the grille with the baffle and turning it clockwise until it securely locks in. [. . . ]